State of the art systems for occupant classification and detection are foil based systems which are integrated in every single seat (involving high integration costs). It is also known to provide for contactless sensing (e.g. of humans) within a vehicle, e.g. for occupancy detection (OD), occupancy classification (OC) or seat-belt reminder (SBR) functionality. Radar based in-vehicle systems are not established on the market due to high costs. In general, each single seat needs a separate radar sensor.
Radar technology offers some advantages in comparison to other occupancy detection and classification methods. It is a contactless and invisible measurement system which can easily be integrated behind plastic covers and textiles. Radar systems can measure the smallest motions within the range of micrometers. Existing state of the art solutions use a conventional single frequency Doppler radar as a motion sensor. This is not sufficient in order to get a reliable indication of the occupancy status or of whether the human is inside or outside the car.